This invention relates, in general, to spin-on glass (SOG) and, more particularly, to thick film spin-on glass used in semiconductor processing.
The use of spin-on glass is well known in the art of semiconductor processing but is limited in usable thickness. Presently, the maximum thickness utilized for spin-on glass is approximately 2000 Angstroms. Using films thicker than this cause the glass layer to become highly stressed which results in cracks developing during processing. If a thicker glass layer is desired, it would have to be put down in multiple layers separated by chemical vapor deposition (CVD) oxide. Even using multiple layers, it has been found that the maximum thickness is 4000 Angstroms, or two layers of 2000 Angstroms each separated by the CVD layer. The reason for this limitation is that the lower SOG layer cannot support more than one additional SOG layer during processing.
In addition, present experimental spin-on glasses have a shelf life of approximately one month. This makes it difficult to maintain stocks of large quantities and is greatly effected by shipping or processing delays.
Further, present attempts to make thick film spin-on glass are subject to: being detached from the substrate during normal chemical processing; or, simply falling off the substrate. These relate to adhesion and wetting problems.
Therefore, it is an object of the present invention to provide a spin-on glass that overcomes the above deficiencies.
A further object of the present invention is to provide a spin-on glass that can be utilized as a thick film in semiconductor processing.
Another object of the present invention is to provide a spin-on glass having an improved shelf life.
Still another object of the present invention is to provide a spin-on glass having improved adhesion and wetting characteristics.
Yet another object of the present invention is to provide a spin-on glass preferably having between 11.0 and 9.0 atomic weight percent carbon.
The above and other objects and advantages of the present invention are provided by the spin-on glass described herein.